Methods of making abrasive wheels



J. L. HENSLEY June 7, 1966 Filed Dec.

June 7, 1966 J. 1 HENsLEY 3,255,289

METHODS OF MAKING ABRASIVE WHEELS Filed Dec. 6, 1961 2 Sheets-Sheet 2Fig, 6 INVENTOK JAMES L. HENSLEY BY MAM,

ATTORNEYS United States Patent O 3,255,239 METHODS F MAKING ABRASIVEWHEELS James L. Hensley, Knoxville, Teun., assignor, by mesneassignments, to Tysaman Machine Company, Inc., Knoxville, Tenn., acorporation of Delaware Filed Dec. 6, 1961, Ser. No. 157,514 4 Claims.(Cl. 264-316) This invention relates to improvements in methods ofmaking abrasive wheels, particularly of the character used for cut-oitmachines.

One method of manufacturing abrasive wheels involves the use of acircular type press. The desired quantity of abrasive material is forcedinto the mold and spread over the area thereof. This material usually ismade of abrasive particles combined with a binder capable of beingpressed and hardened to form a disc. a disc may be made up tothirty-four inches in diameter and seven thirty-seconds inch thick. Atop mating pressure plate is used to press the material to the desiredshape and density.

Thereafter, the wheel thus formed is removed from the press for curing.It must be kept flat until fully cured and ready for use. If laidwithout support over the entire area thereof, the wheel is subject -towarping,taking a permanent set out of atness, which would destroy itsusefulness.

In the use of an labrasive wheel, especially of large diameterl size,and in making deep cuts, the wheel is subject to many adverse operatingstresses, such as excessive side binding which required increased powerto continue the operation thereof. Moreover, cooling of the wheelbecomes difficult in making deep cuts.

It has long :been known that the wheel would be improved by making therim section thicker than the web section inwardly of the rim, but nosatisfactory Way has been found lheretofore of-making the wheel with athicker rim and maintaining it in condition for use. An attempt hasibeen made to shape the press to form a uniform taper in the web sectioncontinuously from the peripheral edge of the rim to the center. Thisleft a feather edge that was not sulicient to prevent side travel.Moreover, it required a pallet having a supporting surface complementaryto the surface of the wheel to support the latter to prevent distortionto one lllat side during curing and continuously until put intosubstantial use.

One object of this invention is to overcome the objec- -tions toabrasive wheels with straight sides and -to improve the method of makingabrasive wheels.

Another object of the invention is to provide in the method ofmanufacturing an abrasive Wheel with a thickened rim, of support meanstherefor within the face of the wheel and readily removable when thewheel is ready to be put t'o use..

Still :another object of the invention is to provide for molding anabrasive wheel upon a separate core placed within the mold and of.appreciably smaller area than the area of the mold and wheel and moldedin the surface of the wheel to rbe removed from the mold therewith butcapable of ready separation from the wheel when the latter is to 4beused.

These objects may be accomplished by placing one or more sheets ofmaterial in the bottom of the mold and of appreciably less area than thearea of the mold, and also of appreciable composite thickness so as toform a web section of less thickness than the thickness of the rimsection. The material used in the mold can be of varying or Vany desiredthickness according to the amount of stepped Frequently, such ice taperdesired in the finished Wheel. A like number of shee-ts of materialpreferably are used under -the pressure plate on top of the compositionfor a properly balanced wheel. 'These sheets would adhere to the formedwheel and remain thereon after removal from the mold and duringA curing,and, in fact, until the wheel is ready for use.

This method is illustrated in the accompanying drawv ings, in which: I

. FIG. l is a cross section through a mold showing layers of moldingmaterial to be .applied to opposite sides of an abrasive wheel in themolding thereof; A

FIG. 2 is a cross section through the molded wheel after removal fromthe mold;

FIG. 3 is a similar View of the wheel ready for use;

FIG. 4 is .a cross section of the wheel in the work;

FIG. 5 is a plan View of a modied form of wheel;

FIG. 6 is a detail perspective view of 4the modified abrasive lwheelmade with molding -sheets of material of the character illustrated inFIG. 5; and

FIG. 7 is a sectional view of the modilied abrasive wheel in the work.

The relative sizes and dimensions of parts are exaggerated in thedrawings for clearness of illustration.

'The invention is illustrated in connection with a mold of conventionalform for clarity of illustration. This mold comprises top ,and bottomplatens 1 and 2 shaped to mold a mass of abrasive plastic material toform a wheel of the desired contour and size.

The bottom platen 2 isA provided with a cylindrical cavity 3 having abottom face 4 usually smooth and flat.

The under surface l5 of the top platen 1 is also usually flat and smoothcontinuously throughout the area of the -top platen 1.

The means for forming the center hole in the wheel is illustrated as apin 6 rising from the lbottom cavity face 4 and of la length to extendentirely through the mold cavity. Any suitable means may be used for thepurpose.

In making a wheel according to this invention, the moldable abrasivematerial is placed in the mold cavity 3 of a quantity according to Ithesize and thickness of the wheel to be made, after which the t-op platen1 may be applied thereto to effect the molding'operation in the usualway. Suitable pressure is applied to the top platen and held for alength of time suiiicient to effect the molding operation. Lining sheetsa and b are shown in FIG. 1 extending over and throughout the respectiveareas of the surfaces 4 and 5 t-o facilitate separation of the moldedwheel therefrom. These lining sheets may be used if desired, but are notrequired according to this invention.

The abrasive wheel is illustrated in FIGS. 2 to 4, made with a thick'rimsection R and a lrelatively thinnerl web section W. This relativelythinner web section W is formed by one or more'molding sheets on eitheror both sides of the mold cavity. In the example illustrated., suchmolding sheets are shown at c, d and e stacked flatwise on the bottomface 4 of the cavity 3, and also three such molding sheets are shown atf, g and h stacked against the bottom face 5 of the top platen or thelining sheet b, if used.

Each of the molding sheets c to h extends symmetrically of the moldcavity but has its periphery spaced inwardly an appreciable distancefrom the periphery of the cavity. The largest diameter sheet or sheetsthereof are at the inner periphery of the rim R. Y Where several sheetsare used in each stack these form shoulders S on the face or faces ofthe wheel in one or more steps between the rim R and the web W of thewheel. v

The molding sheets c-h may 4be held in placein any suitable manner inthe mold cavity and on the undersurface of the top platen 1. The sheetor sheets in the bottom of the cavity may be provided with centralopenings to t around and on the central pin 6. In like rrianner, thesheet or sheets that are secured to the undersurface of the top platen lmay be held in place around the opening in the bottom face of thatplaten in which the pin 6 is received when the platen is inserted in thecavity. Suitable means should be provided on the top platen to hold thesheets thereto, but to allow ready separation therefrom when the topplaten is removed from the mold.

The molding sheets c-z may be formed of any suitable material founddesirable for the purpose, such, for example, as kraft paper, wax paper,or aluminum foil. The material should .be such as would enable the sheetor sheets to be peeled readily from the formed abrasive disc or wheelwhen the latter is to be put into service. The molding sheet, if one isused on each surface, or the composite sheets if more than one are usedon each surface, should 'be of suflicient thickness so as to separatethe web section W from the rim section R and to provide a delinitelythicker -rim section than the we-b section, as somewhat exaggerated inFIGS. 3 and 4. The greater thickness, nevertheless, of the rim sectionshould be such as will provide a radial addition to the rim of uniformthickness so as to provide denite support for the Wheel in the kerfformed in the material to prevent side travel of the wheel in operation.At the same time, the spacing of the web portion from the sides of the`formed kerf permits free access of the cooling liquid to the rim andsubstantially throughout the area of the wheel to obtain maxi mumcooling effect.

After molding the wheel with the .molding sheets embedded therein, thewheel is removed from thev mold and cured in the usual manner. Themolding sheets remain in place on the wheel until the latter is -readyfor use. Then they may be peeled off or separated, so as to provide forthe operation of the wheel in the usual manner. When in place on thewheel, the molding sheets provide uniform support for the wheel, bothduring curing and during handling or storage.

Usually, these molded abrasive wheels are supported flat and theyrequire support continuously throughout the area of each to prevent thepossibility of distortional warpage. By molding the sheets directly inthe surface of each wheel, the sheets 4remain in the wheel embedded-therein and support the surface uniformly throughout.

Moreover, the provision of molding sheets in the cen- -ter portion ofthe wheel, spaced inwardly from the surrounding rim section, providesfor greater pressure being applied to this center section, which willcompact the moldable abrasive material with greater density than in thelrim section. Thus, the wheel will harden more etectively in the centerand produce a more durable wheel ythan one of uniform densitythroughout.

It is also possible to use molding sheets to modify the surface of theabrasive wheel in other respects than has 'been illustrated in FIGS. lto 4. One such sheet would 'be used in the `bottom of the cavity andanother preferably in the top thereof under the top platen. When theabrasive material is thus deposited in the cavity between the sheets, awheel would be molded in the usual manner, as indicated at W in FIG. 6.Such `a wheel would have alternate lribs and grooves extending radiallythereof on one or both opposite faces of the wheel, which would -liaveexcellent cutting and cooling effect and would minimize side bindingduring the operation of the wheel, as will be apparent from FIG. 7. Thealternate g-rooves and ribs will provide courses W2 for the coolingliquid to flow radially outward along the wheel entirely to theperiphery thereof from the center portion W3 thereof during theoperation of the cutting of metal, stone or other materials. In otherrespects the method of use and of manufacture illustrated in FIGS. 5 to7 would be the i same as set forth above and involve the use of similarmaterials.

While the invention has been illustrated and described in certainembodiments, it is recognized that variations and changes may 'be madetherein without departing from the invention set forth in the claims.

I claim:

1. A method .of making an abrasive wheel having a thicker peripheral rimand a thinner central web comprising introducing a mass of moldableabrasive material into a circular cavity and extending continuously overthe area thereof, applying molding sheets between opposite sides of thecavity and the moldable Imaterial and of an area covering the majorportion of the area of the cavity but smaller than the area of thecavity, pressing and -molding the material in the cavity forming acontinuous rim yaround the periphery of the sheets and a central webportion between the sheets, removing the formed wheel with the sheetsthereon from the cavity, and thereafter peeling the sheets from thesurfaces of the wheel.

2. A method of preparing .for use an abrasive wheel comprising applyingHat molding sheets to opposite faces of a circular molding cavity havingappreciably greater diameter than the depth of tlie cavity to formopposite side faces of the wheel and of an area to cover the majorportion of the side face area of the cavity but less than the entirearea thereof, introducing into the cavity between the sheets a plasticmolding .material having abrasive particles embedded therein andextending continuously as one mass over substantially the entirecircular area of the cavity, pressing and molding the material in thecavity with the sheets embedded in said opposite faces and with a spacebetween the periphery of the sheets and the periphery of the cavityforming a rini on the wheel, removing said formed wheel from the cavitywith the sheets embedded in the surfaces thereof, and thereafter peelingthe sheets from the surfaces of the Wheel.

Ei1 A method of preparing for use an abrasive Wheel having a surroundingrim and with a web portion of less thickness than the rim for thecirculation of a cooling fluid 'by the web portion to the rim, saidmethod comprising introducing into a circular mold cavity and spreadingover the area thereof a uniform mass of moldable plastic material havingabrasive particles embedded therein and with a plurality of thin moldingsheets at opposite sides of said mass of material between the latter andthe adjacent faces of the cavity at the center portion of the cavity,applying pressure to said material until the mate- -rial is set to forma wheel and with the material between the sheets forming the webportion, removing the formed wheel from the cavity with the sheets inplace embedded therein to support the web portion when the wheel is laidon its side face until use, and said sheets being adapted to be removedfrom the side faces before use.

4. A method of making an abrasive wheel having a peripheral portionthicker than the center portion thereof, said method comprising applyinga plurality of thin circular molding sheets in the bottom of a circularmolding cavity coaxially thereof and of each other and with the sheetsof progressively larger diameter from top to bottom of said plurality,spreading over the area of the cavity and over the plurality of sheets auniform mass of plastic material having abrasive particles embeddedtherein, superposing over the mass of material a second plurality ofthin circular molding sheets of progressively larger diameter from`bottom to top thereof, placing a compression member over the secondplurality of sheets, applying pressure to the assemblage to cause themass to ow and form a wheel in the cavity, and removing the formed Wheelfrom the cavity with both plurality of sheets in place during storage,and said sheets being adapted to be removed therefrom before use.

(References on following page) References Cited by the Examiner UNITEDSTATES PATENTS Arthur 51-209 Bell 264-259 Harvey 51-209 Goepfert et zal.18-59 Belcher 51-206 ROBERT F.

Reidenbach 51-209 Von Doenhoff 51-206 Davis 264-259 Sucher 264-316WHITE, Primary Examiner.

ALEXANDER H. BRODMERKEL, Examiner.

1. A METHOD OF MAKING AN ABRASIVE WHEEL HAVING A THICKER PERIPHERAL RIMAND A THINNER CENTRAL WEB COMPRISING INTRODUCING A MASS OF MOLDABLEABRASIVE MATERIAL INTO A CIRCULAR CAVITY AND EXTENDING CONTINUOUSLY OVERTHE AREA THEREOF, APPLYING MOLDING SHEETS BETWEEN OPPOSITE SIDES OF THECAVITY AND THE MOLDABLE MATERIAL AND OF AN AREA COVERING THE MAJORPORTION OF THE AREA OF THE CAVITY BUT SMALLER THAN THE AREA OF THECAVITY, PRESSING AND MOLDING THE MATERIAL IN THE CAVITY FORMING ACONTINUOUS RIM AROUND THE PERIPHERY OF THE SHEETS AND A CENTRAL WEBPORTION BETWEEN THE SHEETS, REMOVING THE FORMED WHEEL WITH THE SHEETSTHEREON FROM THE CAVITY, AND THEREAFTER PEELING THE SHEETS FROM THESURFACES OF THE WHEEL.